The present invention relates to the technology to emphasize a sound image by an acoustic processing of an audio signal.
In playing the music, it is requested that various sound field effects should be attached by applying the acoustic processing to the audio signals to be emitted as the sounds. As an example in attaching such sound field effect, four speakers are provided in front left, front right, rear left, and rear right sides of the listener, and the acoustic processing is applied to the audio signals emitted from respective speakers and the sounds are emitted, so that reflected sound in various directions are reproduced. Also, only two speakers are provided in front left and front right sides, the technology to attach the similar sound field effect is disclosed (for example, Patent Literature 1).
[Patent Literature 1] JP-A-6-261398
According to the technology set forth in Patent Literature 1, various sound field effects can be attached by two speakers provided in front left and front right sides of the listener. In this case, even when the audio signals are the stereo signals, the sound field effect is attached by executing the acoustic processing after the stereo signals are converted into the monaural signal that is obtained by synthesizing the right-channel signal and the left-channel signal. Therefore, a stereo feeling is lost in reproducing the initial reflected sound, and also sometimes an emphasizing effect of the sound source and a stereophonic effect are lost.